text: The Borda–Carnot equation gives the decrease in the constant of the Bernoulli equation. For an incompressible flow the result is for two locations labelled 1 and 2, with location 2 downstream to 1 along a streamline:
  with
  : p and p the pressure at location 1 and 2,
  : z and z the vertical elevation (above some reference level) of the fluid particle,
  : g the gravitational acceleration.
  The first three terms on either side of the equal sign are respectively the pressure, the kinetic energy density of the fluid and the potential energy density due to gravity. As can be seen, pressure acts effectively as a form of potential energy.
  In case of high-pressure pipe flows, when gravitational effects can be neglected, ΔE is equal to the loss Δ(p + ρv/2):
  For open-channel flows, ΔE is related to the total head loss ΔH as
  with H the total head:
  where h is the hydraulic head the free surface elevation above a reference datum: h = z + p/(ρg).